The cell coat or glycocalyx, rich in glycoproteins, plays a role in many interactions of cells with their microenvironment and with each other. Indeed, alterations in the composition of the cell coat accompany malignant changes of many cell types including the epithelial cells of the colon. It has been established that cell coat glycoproteins receive some of their carbohydrates in the Golgi apparatus. The cell coat material in the columnar epithelial cells of the ascending colon of the mouse is then transported to the cell surface by vesicles. However, 1) the requirement for normal glycosylation for maintenance of this system is unknown, and 2) the means by which these vesicles are moved to the surface has not been defined. In the current study inhibitory drugs are being used to address these two problems. Their effects are being observed in mouse colonic cells. 1) Diazo-oxo-norleucine and tunicamycin inhibit the addition of carbohydrates to glycoproteins. The effects of these drugs on the organelles involved in the formation of cell coat are being analyzed by electron microscopy (EM) and EM cytochemistry. 2) Colchicine inhibits intracellular movement associated with microtubules. It is likely that the directed movement of glycoprotein carrying vesicles toward surface membranes is associated in some manner, with microtubules. However, since the role of these vesicles appears to differ somewhat from secretory vesicles, their interaction with microtubules requires investigation. Using cytochemistry and radioautography at the level of fine structure, we will a) determine whether movement of this type of vesicle is curtailed by interference with microtubules and, if so, b) the effects on cell coat maintenance and turnover when continual replacement of this material is disrupted.